Vehicles are outfitted with pressure relief valves for ventilating the passenger compartment of the vehicle and for preventing a sudden build up of air pressure within the passenger compartment. The air pressure within the passenger compartment of a vehicle may rise suddenly, for example, when a door of the vehicle is slammed shut.
A typical pressure relief valve includes one or more openings. A movable gate covers each opening in the pressure relief valve. The gate operates to cover and uncover the opening in response to a differential pressure across the pressure relief valve. When the air pressure within the passenger compartment is greater than the atmospheric pressure by a predetermined amount, the gate moves to uncover the opening enabling airflow out of the passenger compartment to atmosphere. When the air pressure within the passenger compartment is less than or equal to the atmospheric pressure, the gate covers the opening to prevent airflow from the atmosphere into the passenger compartment. Thus, the typical pressure relief valve acts as a check valve.
The gate of the typical pressure relief valve does not completely seal over the opening in the pressure relief valve. As a result, some airflow may enter the vehicle compartment through the pressure relief valve when the gate covers the opening. Any entering airflow may include noise from outside of the vehicle. The noise entering the pressure relief valve increases the passenger detectable noise within the passenger compartment. It is desirable to reduce the amount of atmospheric noise that is detectable within the passenger compartment.
One known method for decreasing the amount of noise passing through the pressure relief valve into the passenger compartment includes placing a noise absorbing pad near an interior of the pressure relief valve. As a result, much of the noise entering the passenger compartment through the pressure relief valve passes through the opening in the pad.